Viral genome packaging terminase cleaves DNA using the canonical RuvC-like two-metal catalysis mechanism.

ABSTRACT: Bacteriophages and large dsDNA viruses encode sophisticated machinery to translocate their DNA into a preformed empty capsid. An essential part of this machine, the large terminase protein, processes viral DNA into constituent units utilizing its nuclease activity. Crystal structures of the large terminase nuclease from the thermophilic bacteriophage G20c show that it is most similar to the RuvC family of the RNase H-like endonucleases. Like RuvC proteins, the nuclease requires either Mn2+, Mg2+ or Co2+ ions for activity, but is inactive with Zn2+ and Ca2+. High resolution crystal structures of complexes with different metals reveal that in the absence of DNA, only one catalytic metal ion is accommodated in the active site. Binding of the second metal ion may be facilitated by conformation

SUBMITTER: Xu RG 

PROVIDER: S-EPMC5389553 | biostudies-literature | 2017 Apr

REPOSITORIES: biostudies-literature